1. Field of the Invention
The present invention relates to a composition for obtaining a vulcanized rubber comprising an epihalohydrin rubber as a main component improved with heat resistance and a vulcanized product obtained by vulcanizing the composition.
2. Description of the Prior Art
Epihalohydrin rubber materials have been widely used in the application use of automobiles as materials for fuel hoses, air hoses and tubes while taking advantages such as heat resistance, oil resistance and ozone resistance thereof. Further, while epihalohydrin rubbers have been obtained so far by vulcanization using thiourea type vulcanizing agents and lead-based acid acceptors, the vulcanizing agent-acid acceptor systems have some concern in view of the toxicity of lead and toxicity of the vulcanizing agent and, further, the vulcanization rate is not sufficient as well.
Further, as the vulcanizing agent for the epihalohydrin rubber, a mercaptotriazine vulcanizing agent (JP-B No. 48-36926), a quinoxaline vulcanizing agent (JP-A No. 56-122866), etc. have been known and since the vulcanizing rate can be improved to obtain products of good heat resistance by using the vulcanizing agents, they have been popularized generally.
On the other hand, as the acid acceptors to be combined with the vulcanizing agents, magnesium oxide, lead compound, zinc oxide, synthetic hydrotalcite, slaked lime, quick lime, etc. have been properly selected in accordance with required characteristics for the rubber materials such as store stability, mechanical property, compression set property, ozone resistance, cold resistance, and oil resistance, processing method of rubber materials, economicity of vulcanizing agents, etc. Further, as a vulcanization accelerator, general vulcanization accelerators for rubbers, quaternary amine compounds, quaternary phosphonium salts, etc. have been used. (JP-A No. 59-227946)
However, emission regulation and regulations for fuel evaporation for automobiles have become increasingly severer in recent years and, further, along with low fuel cost, improvement in the performance of engines, and need for maintenance-free parts, a further improvement in the heat resistance has been demanded for rubber materials for use in automobiles.